Studying New York City's Crime Decline: Methodological Issues

Methodological issues that must be considered in doing research on the New York City crime drop include the choice of a spatial unit of analysis, the choice of a mathematical representation of the processes responsible for the drop, and the choice of estimators. This paper considers the strengths and weaknesses of a time series analysis of data for New York alone, a panel analysis for the city's precincts, and a panel analysis for a sample of cities, for studying the drop. The possibilities and limitations of precinct-level data are illustrated with annual precinct data for New York between 1988 and 2001. The paper considers static and dynamic fixed effects panel models estimated in various ways, including difference and systems generalized method of moments. These analyses find no evidence that misdemeanor arrests reduced levels of homicide, robbery, or aggravated assaults. Felony arrests reduced robberies, but only to a modest degree. Most of the decline in these three felonies had other causes.